Nanoemulsions with oleoresin of Copaifera reticulata (Leguminosae) improve anthelmintic efficacy in the control of monogenean parasites when compared to oleoresin without nanoformulation

This study compared the in vitro anthelmintic activity of Copaifera reticulata oleoresin (200, 400, 600, 800 and 1,000 mg/L) and of nanoemulsions prepared with this oleoresin (50, 100, 150, 200 and 250 mg/L) against monogeneans on the gills of Colossoma macropomum. The major compounds present in the oleoresin of C. reticulata were γ-macrocarpene (14.2%), α-bergamotene (13.6%), β-selinene (13.4%) and β-caryophyllene (11.7%). All concentrations of the nanoemulsion and the oleoresin without nanoformulation showed anthelmintic efficacy against monogeneans, and higher concentrations led to more rapid parasite mortality. Structural damages to the tegument of the parasites exposed to C. reticulata oleoresin were observed with scanning electron microscopy. At two hours of exposure, fish showed 100% tolerance to all nanoemulsion concentrations used in the in vitro assays, whereas 100% mortality was shown in the fish exposed to the oleoresin without nanoformulation after one hour. The results of this study suggest that nanoemulsions with oleoresin of C. reticulata have advantages in the control and treatment of monogenean infections in C. macropomum when compared to the oleoresin without nanoformulation. In addition, since nanoemulsions with the C. reticulata oleoresin are safe to control monogeneans, the efficacy of these nanoformulations may be assayed in therapeutic baths to treat C. macropomum infected by monogeneans.     

Effects of a nanoemulsion with Copaifera officinalis oleoresin against monogenean parasites of Colossoma macropomum: A Neotropical Serrasalmidae

Monogeneans are ectoparasites that may cause losses in production and productivity in the aquaculture of Colossoma macropomum. Chemotherapeutics used in aquaculture usually have major adverse effects on fish; hence, the use of essential oils has been considered advantageous, but these are not soluble in water. Thus, the use of nanostructures to enhance water solubility of compounds and improve bioactivity may be very promising. This study investigated the antiparasitic activity of nanoemulsion prepared with Copaifera officinalis oleoresin (50, 100, 150, 200 and 300 mg/L), against monogenean parasites from the gills of C. macropomum. The particle size distribution and zeta potential suggested that a potentially kinetic stable system was generated. The nanoemulsion from C. officinalis oleoresin achieved high efficacy (100%) at low concentrations (200 and 300 mg/L) after 15 min of exposure. This was the first time that a nanoemulsion was generated from C. officinalis oleoresin using a solvent‐free, non‐heating and low‐energy method. Moreover, this was the first time that an antiparasitic against monogeneans on fish gills, based on nanoemulsion of C. officinalis oleoresin, was tested.     

Essential oil of Lippia grata (Verbenaceae) is effective in the control of monogenean infections in Colossoma macropomum gills,a large Serrasalmidae fish from Amazon

This study investigated the efficacy of Lippia grata essential oil (EO) against monogeneans of Colossoma macropomum and effects on the haematology after immersion baths. In the in vitro assays, the efficacy of 100, 250, 350 and 700 mg/L of L. grata EO and two controls were tested, of which one control was with the cultivation tank water and the other was with the tank water and 70% ethyl alcohol. Composition of majority bioactive compounds in the EO was carvacrol (48.12%), p‐cymene (24.39%) and γ‐terpinene (2.49%). Anacanthorus spathulatus, Notozothecium janauachensis, Mymarothecium boegeri and Linguadactyloides brinkmanni obtained of fish gills showed 100% immobilization in the in vitro assays when exposed to 700 and 350 mg/L after 30 min and 2 hr respectively. Fish showed tolerance to 700 mg/L of the EO, which was used in therapeutic in three consecutive baths, which caused lamellar hyperplasia in C. macropomum gills. The 700 mg/L of the EO in the therapeutic baths showed an efficacy of 95.1% against the monogeneans and caused decrease in haemoglobin, whereas control fish showed a reduction in mean corpuscular haemoglobin concentration. Results indicated that 700 mg/L of L. grata EO is a safe and effective concentration to treat C. macropomum infected with monogeneans.     

Albendazole,levamisole and ivermectin are effective against monogeneans of Colossoma macropomum (Pisces: Serrasalmidae)

This study evaluated the efficacy of albendazole, ivermectin, levamisole, mebendazole and praziquantel on monogeneans of Colossoma macropomum, based on in vitro and in vivo assays. In vitro assays indicated that albendazole (500, 100, 1,500 and 2,000 mg/L), ivermectin (200, 250, 300 and 350 mg/L) and levamisole (50, 75, 100 and 125 mg/L) were 100% effective against Anacanthorus spatulatus, Notozothecium janauachensis, Mymarothecium boegeri and Linguadactyloides brinkmanni, while mebendazole (125, 150, 175 and 200 mg/L) and praziquantel (5, 10, 15 and 20 mg/L) were ineffective. Fish mortality in 24 hr therapeutic baths with 500 mg/L of albendazole was 6.6%, but the behaviour of the animals remained unchanged, while 200 mg/L of ivermectin caused lethargy, signs of hypoxia and 100% mortality within 2 hr, and 125 mg/L of levamisole caused no mortality. The efficacy of 500 mg/L of albendazole was 48.6% in the 24 hr baths, while that of 125 mg/L levamisole was 88.2%. Although ivermectin showed in vitro efficacy, the lowest concentration used in baths was highly toxic to fish. Therefore, we recommend the use of 125 mg/L of levamisole to control and treat monogenean infestations on C. macropomum in fish farming.     

Efficiency of 2‐phenoxyethanol and Clove Oil for Reducing Handling Stress in Reared Meagre,Argyrosomus regius (Pisces: Sciaenidae)

The effect of two anesthetics, 2‐phenoxyethanol (2‐PE) and clove oil (COil) were studied in meagre, Argyrosomus regius. This study aimed to determine the adequate dose of anesthesia for different aquaculture procedures, to assess a sedative or stressor effect of low anesthetic concentrations, and to assess the effect of low anesthetic doses at high fish densities for longer periods of time on fish survival and behavior. Anesthetics were tested at different concentrations: 2‐PE at 100, 250, 400, 550, and 700 mg/L; COil at 25, 40, 55, 70, and 85 mg/L. Meagre became anesthetized within 10 min when using concentrations above 250 mg/L for 2‐PE and above 40 mg/L for COil. Deep anesthesia was achieved at 700 and 85 mg/L, for 2‐PE and COil, respectively. The fish did not react when blood was collected at these concentrations. Plasma cortisol and glucose levels were similar between sedated meagre with both 2‐PE – 100 mg/L and COil – 10 mg/L, and the control (not sedated; P > 0.05). This suggests that low concentrations of these anesthetics induce similar stress response as handling without anesthesia during routine activities. No mortality was registered when meagre was maintained at high densities with low concentrations of each anesthetic for 2 h.     

Assessment of induction and recovery times of anaesthesia in Astyanax bimaculatus using 2‐phenoxyethanol and the essential oils of Melaleuca alternifolia and Ocimum gratissimum

This study aimed to determine the lowest effective concentration (LEC) of 2‐phenoxyethanol (2‐Phe) and essential oils (EOs) of Melaleuca alternifolia and Ocimum gratissimum able to induce anaesthesia in Astyanax bimaculatus. LEC was assumed to be the required concentration to carry out anaesthesia in less than 3 min with recovery in <5 min and sufficient to carry out routine aquaculture procedures. The following concentrations were tested: 2‐Phe (100, 200, 300, 400, 500 and 600 µl/L); M. alternifolia (200, 300, 400, 500 and 600 µl/L); and O. gratissimum (10, 20, 30, 40, 50, 60, 70, 100, 150, 250 and 300 µl/L). Results show that all three agents evaluated have effective anaesthetic properties for use in Astyanax bimaculatus with LEC for 2‐Phe, M. alternifolia and O. gratissimum of 200, 300 and 60 µl/L respectively.     

Finishing plant diet supplemented with microalgae meal increases the docosahexaenoic acid content in Colossoma macropomum flesh

The need for a sustainable aquaculture is increasing the use of plant ingredients in replacement to fishmeal and fish oil in diets for tambaqui Colossoma macropomum, which is leading to not detectable levels of docosahexaenoic acid (DHA) in its flesh. We evaluated the effect of a finishing plant diet supplemented with 5% of microalgae meal from Schizochytrium sp. (MD) on tambaqui growth, on proximal composition and fatty acid content of its flesh, comparing it to a non‐supplemented diet. One hundred and sixty‐two fish (489.67 g) were distributed into six tanks (2,000 L) and fed the experimental diets for a 90‐day period. Three fish per tank were euthanized for analyses every 15 days. The MD did not affect the growth and proximal composition of fish flesh. The MD increased the DHA content (from 14.81 to 38.60 mg/g of lipids) and the n‐3:n‐6 ratio (from 0.16 to 0.51) in the flesh of fish, beginning on the 15th day and reaching the highest DHA content on the 71st day (39.81 mg/g of lipids). We recommend C. macropomum to be fed with a finishing diet supplemented with microalgae meal for 71 days before slaughter to improve the DHA content and n‐3:n‐6 ratio in the flesh.     

Effects of antimicrobial peptides on growth,morphology of foregut villi and related genes mRNA expression in the common carp (Cyprinus carpio)

A 60‐day feeding trial was conducted to examine the effects of different levels (0, 100, 200, 400 and 600 mg/kg) of antimicrobial peptides on growth, protease activity of foregut, the morphology of foregut villi and related genes mRNA expression level in the common carp (Cyprinus carpio). The results showed that the feed of antimicrobial peptides promote common carp growth, and the optimal dosage of antimicrobial peptides is 200–333 mg/kg in the common carp feed. The protease activity of 200 and 400 mg/kg groups were significantly higher than the control and other groups (p < 0.05). The foregut villus height with 100, 200 and 400 mg/kg antimicrobial peptide groups were significantly higher than control group (p < 0.05). The crypt depth of 200 and 400 mg/kg antimicrobial peptide groups were significantly lower than control group (p < 0.05). The ratio of villus height and crypt depth of 100, 200 and 400 mg/kg antimicrobial peptide groups were significantly higher than control group (p < 0.05). The ratio with 600 mg/kg group was significantly lower than the control group (p < 0.05). The IGF‐I gene expression level of 200 mg/kg and 400 mg/kg groups were significantly higher than the control group and 600 mg/kg group (p < 0.05). The IL‐1β gene expression level of 100 mg/kg and 200 mg/kg groups were significantly higher than the control group (p < 0.05). These results indicated up‐regulation of growth and immune related genes in antimicrobial peptides fed common carp. Correlation analysis showed that IGF‐I mRNA and IL‐1β mRNA were positively correlated with SGR. IL‐1β mRNA and FCR were significantly negative correlated. It indicated that growth and immune gene common regulated the growth of the carp under antimicrobial peptides intervention. In conclusion, antimicrobial peptides can improve growth and related genes mRNA expression in the common carp. Further studies using molecular biological technique or immunologic methods are required to conclude that antimicrobial peptides are beneficial in common carp.     

Effects of dietary chlorogenic acid on growth,flesh quality and serum biochemical indices of grass carp (Ctenopharyngodon idella)

The study was to investigate effects of dietary chlorogenic acid (CGA) on growth performance, flesh quality and serum biochemical indices of grass carp (95.1 ± 0.3 g) (Ctenopharyngodon idella) fed seven different diets, including control diet, Eucommia ulmoides (EU)‐supplemented diet (20 g kg^–1) and CGA‐supplemented diets containing 100, 200, 400, 600 and 800 mg/kg CGA. Contents of collagen and alkaline‐insoluble collagen in muscle and skin were significantly increased by dietary CGA and EU (p < .05). Total essential amino acids (TEAA) and total amino acids (TAA) in muscle of grass carp fed EU diet or 400, 600 and 800 mg/kg CGA diet were significantly higher than those of fish fed control diet and 100 and 200 mg/kg CGA diet (p < .05). Fish fed 200–800 mg/kg CGA showed significantly lower muscle crude lipid content than EU, control and 100 mg/kg CGA groups (p < .05). Fish fed CGA‐supplemented diets (100–800 mg/kg) had significantly higher muscle fibre density and lower muscle fibre diameter than control group (p < .05). In conclusion, supplementation of CGA improved flesh quality of grass carp, and supplemental level of CGA for improving flesh quality and growth was estimated to be 400 mg/kg diet.     

Disinfection of almaco jack (Seriola rivoliana Valenciennes) eggs: Evaluation of three chemicals

Almaco jack (Seriola rivoliana Valenciennes) is an excellent candidate for aquaculture due to its fast growth rate and high market value. While S. rivoliana have adapted well to captivity, survival at early life stages can be improved to increase profitability during production. A wide range of variables cause larval mortalities but high bacterial loads in rearing tanks are often correlated with these losses. The aim of this study was to investigate the effect of egg disinfection on bacterial load and hatch rate of S. rivoliana. Disinfectants tested included formalin (F100 and F200; 100 and 200 mg/L, respectively, for 60 min), hydrogen peroxide (HPO; 300 mg/L for 10 min) and peracetic acid/hydrogen peroxide (PAA/HPO; 15.7 mg/L/39.6 mg/L for 1 min). Concentrations and contact times were determined based on current use in marine aquaculture and preliminary trials. Eggs treated with HPO and F100 had significantly higher hatch rates than the untreated control group. All treatments significantly decreased total Vibrio counts compared to untreated eggs; however, total bacterial counts were only decreased following treatments with PAA/HPO and F200. To prevent egg mortality due to bacterial overgrowth, consideration should be given to the use of surface disinfection using HPO or F100. Future studies should investigate the use of peracetic‐based products at lower doses.     

Trichlorfon is effective against Dawestrema cycloancistrium and does not alter the physiological parameters of arapaima (Arapaima gigas): A large Neotropical fish from the Amazon

This study investigated the in vitro and in vivo efficacy of trichlorfon against Dawestrema cycloancistrium, as well as its physiological effects on arapaima. Naturally parasitized arapaima gill arches were exposed in vitro to 100, 250, 500 and 750 mg/L of trichlorfon and a control group (only distilled water), in triplicate. Parasites were monitored, and mortality was used to determine the median effective concentration (EC₅₀). The 750 mg/L concentration demonstrated 100% in vitro efficacy against D. cycloancistrium after 60 min, while the intermediate (500 mg/L) and the lowest (100 and 250 mg/L) tested concentrations were completely efficient after 90 and 130 min, respectively. The EC_50-1h of trichlorfon for D. cycloancistrium was determined at 171.73 mg/L. Parasitized arapaima juveniles were exposed to a control group and 150 mg/L of trichlorfon in triplicate. Fish were exposed to two therapeutic baths for 60 min with 24-h intervals between treatments. Therapeutic baths with 150 mg/L of trichlorfon were 92.99% effective against D. cycloancistrium and did not bring about haematological alterations (erythrogram, white blood cell count, thrombogram, plasma glucose and total proteins). Therefore, 150 mg/L of trichlorfon can be used in therapeutic baths to control and treat D. cycloancistrium infestations with no physiological impairments for arapaima.     

Transformation of mugwort (Artemisia vulgaris) oil into nanoemulsion as an ethanol-free herbal anesthetic for surgery on koi carp (Cyprinus carpio)

Fish are frequently anesthetized to reduce stress and injury during various procedures, particularly surgery. Nonetheless, the majority of chemical fish anesthetics have some negative effects on both fish and humans. 2-Phenoxyethanol (2-PE), for example, which is normally used as an anesthetic for ornamental fish, can cause neuropsychological syndromes in humans. To reduce toxicity, some herbal essential oils have been applied as an anesthetic to fish. However, essential oils must be dissolved in ethanol, which has side effects such as disrupting gas exchange in fish. This study aimed to develop mugwort (Artemisia vulgaris) oil as a nanoemulsion without ethanol and determine their optimal concentrations to use as an anesthetic for surgery on koi carp (Cyprinus carpio). Gas chromatography-mass spectrometry (GC/MS) was used to examine the chemical compositions of mugwort oil. The droplet size of mugwort oil nanoemulsion was measured by the dynamic light scattering method. The results revealed that mugwort oil consisted of three major active compounds which were b-pinene (11.7%), 1,8-cineole (10.34%), and a-pinene (8.29%). The average diameter of mugwort oil nanoemulsion droplets was 22.08 ± 0.70 nm. The lowest effective concentrations were 0.6 ml/L for mugwort oil and 12.5 ml/L for mugwort oil nanoemulsion.

     

Antiparasitic activity of the medicinal plant Dillenia suffruticosa against the marine leech Zeylanicobdella arugamensis (Hirudinea) and its phytochemical composition

Zeylanicobdella arugamensis (Annelida: Hirudinea), a marine parasitic leech, is currently affecting different species of cultured groupers, hybrid groupers, snappers and sea bass in Malaysia. Dillenia suffruticosa (Dilleniaceae), a medicinal plant found in Sabah, has been selected in our experiment to kill the leeches as a natural control method. The leech‐infested hybrid groupers were collected from aquaculture facilities, and the isolated leeches were challenged against methanol extract of D. suffruticosa leaves. The experiment was carried out using various concentrations of the extracts such as 25, 50 and 100 mg/ml. The methanol extract showed significant antiparasitic activity against Z. arugamensis with 100% mortality at a concentration of 100 mg/ml in 14.39 ± 3.75 min., followed by 50 and 25 mg/ml in 32.97 ± 9.29 and 41.77 ± 5.40 min., respectively. The phytochemical composition of the extract was determined using GC‐MS analysis to understand the nature of the principal compounds responsible for its antiparasitic properties. The leaves of D. suffruticosa demonstrated the presence of different bioactive compounds of various natures with varying percentages. Thus, it could be revealed that the methanol extract of D. suffruticosa mainly contains vital phytochemical compounds and showed an effective antiparasitic activity against the harmful leeches of hybrid groupers.     

Hatching rate of Chinese sucker (Myxocyprinus asiaticus Bleeker) eggs exposed to total dissolved gas (TDG) supersaturation and the tolerance of juveniles to the interaction of TDG supersaturation and suspended sediment

Flood discharge containing excessive suspended sediments (SS) can result in total dissolved gas (TDG) supersaturation downstream of dams. It has been confirmed that high TDG levels and excessive SS cause serious threats to fish survival. To explore the effects of TDG supersaturation on the hatchability of Chinese sucker (Myxocyprinus asiaticus Bleeker) eggs, eggs were exposed to 100%, 125%, 130% and 135% TDG supersaturated water. The results showed that the hatching rates were 78.25%, 75.35%, 71.30% and 67.50% at the 100%, 125%, 130% and 135% TDG respectively. The hatching rate decreased with increasing TDG levels. Furthermore, acute lethality experiments were carried out to investigate the interaction of TDG supersaturation and SS on Chinese sucker. Half‐year‐old juveniles were exposed to TDG supersaturated water with SS concentrations of 0, 200, 600 and 1,000 mg/L, and the TDG levels were 125%, 130%, 135% and 140% respectively. The fish exhibited abnormal behaviours and signs of gas bubble disease. Mortality increased with increasing TDG levels and SS concentrations. The Chinese suckers only survived for 2.5 hr at 140% TDG and 1,000 mg/L SS. Moreover, an increase in SS in TDG supersaturated water could cause a decrease in the median lethal time (LT₅₀). When the TDG level reached 140%, the LT₅₀ declines significantly at 600 and 1,000 mg/L SS. The interaction of TDG supersaturation and SS was significant at LT₅₀ (F = 22.81, df = 9, p < 0.001). The results indicate that the combined effect of TDG and SS could be great on Chinese sucker.     

Antiviral activities of Clinacanthus nutans (Burm.f.) Lindau extract against Cyprinid herpesvirus 3 in koi (Cyprinus carpio koi)

Cyprinid herpesvirus 3 (CyHV‐3) or koi herpesvirus (KHV) is a virulent viral infection in common carp and koi. The disease has caused global epizootic and economic loss in fish aquaculture and in the wild. Clinacanthus nutans (Burm. f.) Lindau is a well‐known medicinal plant used in Thai traditional medicine. Virucidal effects of the plant extract against human herpes simplex virus have been reported. In this study, C. nutans crude extract was tested for antiviral activities against CyHV‐3 in koi carp. Results showed effective antiviral activity against CyHV‐3 pre‐ and post‐infection. The 50% lethal concentration (LC₅₀) of extract was higher than 5 mg/ml. The 50% effective dose (ED₅₀) was 0.99 mg/ml, 0.78 mg/ml, 0.75 mg/ml and 0.71 mg/ml at 1, 2, 3 and 4 hr pre‐infection, respectively. The ED₅₀ from post‐infection tests was 2.05 mg/ml and 2.34 mg/ml at 0 and 24 hr, respectively. These results demonstrated that crude extract expressed antiviral activity against CyHV‐3 and can be applied as a therapeutic agent in common carp and koi aquaculture.     

Alginate coarse/nanoemulsions containing Zataria multiflora Boiss essential oil as edible coatings and the impact on microbial quality of trout fillet

In this study, the effect of edible coarse/nanoemulsions of alginate as coating containing Zataria multiflora Boiss essential oil (ZEO) on the microbial quality of fish fillets was investigated at three concentrations (i.e. 0.25%, 0.5% and 1% [w/v]) in 16 days of storage at 4°C. Moreover, a comparison was made between the fabricated coarse emulsion and nanoemulsion coatings by particle size and polydispersity index analyses. Sample analysis was performed with regard to total viable count (TVC), total psychrophilic count (TPC), hydrogen sulphide‐producing bacteria count (HSC) and Enterobacteriaceae count (ENC) on days 0, 4, 8, 12 and 16. According to the findings, all the samples showed increased microbial counts during the storage periods. The highest reduction rates of TVC (about 2 log CFU/g), TPC (about 1 log CFU/g), HSC (about 1.5 log CFU/g) and ENC (about 3 log CFU/g) were observed in the nanoemulsion of alginate containing 1% w/v ZEO (NE 1%) samples, compared with alginate and control samples. The microbial growth was significantly inhibited in all treatments, compared with that in the control (p < .05). Accordingly, it can be concluded that nanoemulsion coating was more effective than coarse emulsion to prolong the durability of fish fillets and revealed a faster and greater inhibition of microbial flora, compared with coarse emulsions during the storage time.     

Palm kernel meal (Elaeis guineensis) as a substitute for corn (Zea mays) in diets of Tambaqui (Colossoma macropomum)

Two experiments were carried out to evaluate the effects of palm kernel meal (Elaeis guineensis) as corn (Zea mays) substitutes in tambaqui (Colossoma macropomum) diets based on zootechnical performance, health, characteristics of the muscle, yield and economic efficiency. The first one was carried out in a recirculation aquaculture system for 75 days wherein tambaquis received diets with 0% (T0), 25% (T25), 50% (T50), 75% (T75) and 100% (T100) of corn replacement by palm kernel meal. The second experiment, conducted in ponds for 184 days, tambaquis were fed T0 and T25 diets (selected because showed greater weight gain without health damage). Final weight and weight gain of tambaquis were impaired by the increasing levels of this ingredient on diets, and the feed conversion ratio was worse. The protein efficiency ratio and specific growth rate gradually reduced, while the total number of leucocytes and neutrophils gradually increased. Cholesterol and triglycerides decreased in T75 and T100. Variables analysed in experiment 2 were not affected by treatment, except muscle lipids. Palm kernel meal can replace up to 25% of corn in tambaqui diets since it maintains a balance in economic and zootechnical performance of production.     

Lupin kernel meal as fishmeal replacement in formulated feeds for the Whiteleg Shrimp (Litopenaeus vannamei)

Rapidly expanding global aquaculture requires sustainable, local protein sources to supplement the use of fishmeal. Lupin seed meal (Lupinus angustifolius) was tested as sustainable diet component for Whiteleg shrimp (Litopenaeus vannamei). Controlled feeding experiments were conducted in a recirculating aquaculture system for eight weeks. Juvenile shrimps were provided formulated diets containing various levels of lupin meal inclusion (0, 100, 200 and 300 g kg^?1) supplementing the fishmeal component, and a commercial feed as general reference. Shrimp survival, growth, metabolic and immune parameters were analysed. Survival did not differ significantly between groups. Growth performance was significantly impaired in shrimp fed diets containing more than 100 g kg^?1 lupin meal. Lupin meal supplementation did not affect haemolymph protein content, whereas glucose and acylglyceride concentrations varied between treatments and were highest in animals fed the 100 g kg^?1 lupin meal diet. Phenoloxidase activity was highest in shrimp fed 100 g kg^?1 lupin meal diet indicating improved immune status. The present study indicates that low inclusion levels of lupin meal do not cause adverse effects and seem to stimulate the immune system of juvenile L. vannamei.     

Mass culture of fairy shrimp Branchinecta orientalis (G. O. Sars 1901) (Crustacea: Anostraca) using effluent of rainbow trout Oncorhynchus mykiss (Walbaum 1792) ponds

The variable quality and high price of Artemia (Leach 1819) cyst products, used worldwide as live food, motivate aquaculturists to find an appropriate alternative, especially for fresh/brackish water organisms. In this study, Branchinecta orientalis (G. O. Sars 1901), a common fairy shrimp in north‐western Iran, was reared for 15 days using effluent from trout ponds enriched with effluent filtrate as sole feed, or co‐fed with microalgae (Scenedesmus sp.). The effluent filtrate was replaced by algae at different ratios (25% and 50%), and feeding experiments were designed at densities of 100, 200 and 400 individuals/L in 3‐L containers and at 100 individuals/L in 20‐L containers. The results indicated that, at a certain density, the final length and survival were not significantly affected by different feeding regimes (p > .05). In 3‐L containers, the highest length and survival were observed at the lowest density. B. orientalis contained the highest amounts of proteins, carbohydrates and lipids, though, when co‐fed algae, although the differences with the treatment fed solely effluent filtrate were often limited. Inclusion of algae in the diet also resulted in higher levels of a number of PUFAs. Our study proves that B. orientalis can be mass‐cultured successfully using trout effluent as culture medium without additional microalgae. Fish pond effluent is massively available as a cheap food source. Recycling aquaculture effluent for this type of live food production contributes to lowering the use of natural resources and to less discharge of nutrient loads into natural water bodies.     

Use of neem oil (Azadirachta indica) to control caligid copepod infestation on Asian seabass (Lates calcarifer)

Asian seabass (Lates calcarifer) culture in marine cages have been developed rapidly in Malaysia. The high intensity of culture might facilitate several disease infection including caligid infestation. This study was conducted to evaluate the effect of neem oil (Azadirachta indica) against caligid parasites on seabass. The prevalence and clinical pathogen of Caligus infection has been described through a sampling of 150 fish from floating cage at different cultured periods. Acute toxic tests with different concentrations of neem oil were carried out on the parasite and fish host. Results revealed that the 96‐hr median lethal concentration (LC₅₀) of Caligus and fish (10.3 ± 2.5 g of body weight) were 2 and 20 ppm respectively. The in vivo test indicated that 10 ppm of neem oil could result in 100% antiparasitic efficacy within 96 hr. These results therapeutically demonstrated the efficacy of neem oil in caligid control.